The utility model provides a moisture -proof pad piece, it includes at least one dampproofing surface, be formed with first line structure on this protection against the tide surface, this first line structure is closed ring shape for with the steam separation at the edge on dampproofing surface outside all around. The utility model provides a moisture -proof pad piece, its passageway with product surface formation is kept apart with external environment to steam among the external environment can't touch the product surface, and then can improve the humidity resistance of gasket, thereby can reduce transportation environment and the influence of packing box to the product.